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To address the frequent failure of hydraulic seals under high-pressure and high-flow continuous working conditions, optimizing the seal structure through intelligent optimization algorithms can improve performance. This paper proposes an improved intelligent optimization algorithm and finite element analysis to determine the optimal design parameters for the seal. Initially, a visual inspection and analysis of the failed Y-shaped seal revealed causes such as wear failure, damage failure, and leakage. Finite element analysis of the seal under actual working conditions confirmed the previous analysis. The study considered six control design parameters: lip base height, short-long lip length, short lip height, short lip angle, long lip angle, and lip base fillet radius. Using ANSYS, 50 parameter combinations were selected through Latin hypercube sampling for finite element simulation runs, with the maximum shear stress and maximum contact stress as optimization targets. A BP neural network was established and optimized using a genetic algorithm to design the unequal height Y-shaped seal structure based on NSGA-II, with optimization of the root chamfer to increase net pump backflow. The research results show a 7.29% reduction in maximum contact stress of the seal, a 21.4% decrease in maximum shear stress, and an increase of 0.066 mm3 in net pump backflow through chamfer optimization. The results indicate that this method effectively addresses design issues of seals in industrial applications. [ABSTRACT FROM AUTHOR]

Fluid leakage caused by debonding at the cement interfaces driven by low-temperature fluids is recognized as a significant challenge to wellbore integrity. Previous studies have primarily focused on casing/cement interface debonding, without thoroughly analyzing the simultaneous propagation of debonding fractures at the casing/cement interface and cement/formation interface. Furthermore, prior investigations have been conducted based on hydro-mechanical coupling analysis, neglecting the influence of injection fluid temperature on interface debonding. Therefore, this paper aims to reveal the debonding mechanism of the two cement interfaces using a coupled thermal–hydrological–mechanical (THM) modeling approach. Considering the effect of injected fluid temperature, a 3D numerical model of casing-cement-formation is developed for the simulation of the fluid-driven debonding based on the coupled pore pressure cohesive zone method. The influences of various factors including injection fluid temperature, flow rate, viscosity, casing pressure and cement Young's modulus on the cement sheath debonding are studied, and grey relational analysis is carried out on the influence degree of different factors. The results indicate that the fracture propagation pressure (FPP) is higher, and the fracture height is lower at the casing/cement interface compared to the cement/formation interface. When the fluid temperature is considered by the model, the FPP at the cement sheath interface is lower, and fracture initiation and propagation are more likely to occur. The results also demonstrate that higher fluid temperature, flow rate, viscosity and casing pressure increase the FPP and reduce the risk of cement sheath interface debonding. Casing pressure and fluid temperature exhibit a more prominent influence on FPP. The method can effectively predict the propagation of debonding failures at the cement sheath interface, and provide a foundation for the optimization of injection parameters. Highlights: This paper investigates the simultaneous propagation of the fluid-driven debonding of two cement interfaces considering the injected fluid temperature. A novel numerical model considering the fully coupled thermal–hydrological–mechanical processes is developed. Effects of injection fluid temperature, flow rate, viscosity, casing pressure and cement Young's modulus on the interface debonding are examined. A grey relational analysis is conducted to rank the influence degree of different factors. [ABSTRACT FROM AUTHOR]

Background : Patients on peritoneal dialysis (PD) may develop PD-related complications that necessitate abdominal surgery. However, when to resume PD and how to prescribe PD fluid after surgery in pediatric patients are unknown. Methods: Patients on PD who underwent small-incision abdominal surgery between May 2006 and October 2021 were included in this retrospective observational study. The complications after surgery and characteristics of patients with PD fluid leakage were analyzed. Results: Thirty-four patients were included. They underwent 45 surgical procedures, including 23 inguinal hernia repairs, 17 PD catheter repositioning or omentectomy, and 5 others. The median time to resume PD was 1.0 (IQR, 1.0–3.0) days, and the median PD exchange volume at the initiation of PD after surgery was 25 (IQR, 20–30) ml/kg/cycle. PD-related peritonitis occurred in two patients after omentectomy and one after inguinal hernia repair. There was no PD fluid leakage or hernia recurrence among the 22 patients who had a hernia repair. Peritoneal leakage occurred in 3 of the 17 patients who had PD catheter repositioning or an omentectomy and was treated conservatively. No patients who resumed PD 3 days after small-incision abdominal surgery with less than half of PD volume had fluid leakage. Conclusions: Our findings demonstrated that PD could be resumed within 48 h of inguinal hernia repair with no PD fluid leakage or hernia recurrence in pediatric patients. In addition, resuming PD 3 days after a laparoscopic procedure with less than half of the usual dialysate volume might reduce the risk of PD fluid leakage. [ABSTRACT FROM AUTHOR]

Fluid viscous dampers (FVDs) are the key energy dissipation devices for long-span suspension bridges, and their leakage poses a threat to the stable and reliable operation of bridge restraint systems. Therefore, this paper proposed an FVD fluid leakage diagnosis method based on girder longitudinal displacement monitoring data. First, the longitudinal vibration equation of the main girder under traffic loads was derived to reveal the displacement characteristic of girder-end motion. On this basis, considering that different displacement components under traffic loads are coupled and transient analysis directly utilizing traffic loads as the excitation is complicated and inefficient, an analysis framework focusing on the influence mechanism of FVD leakage on quasi-static displacement was established. Second, an equivalent mechanical model for simulating the hysteresis relationship of leaked FVD was proposed and verified. Then, the influence of variations in the location, number, leakage level and parameters of the leaked FVD on the quasi-static displacement was studied. Third, the equivalent traffic load (ETL) indicator was constructed to characterize the traffic volume. Furthermore, a quasi-static cumulative displacement and ETL correlation model, which can effectively eliminate the interference of traffic flow variations, was proposed for the leakage diagnosis of FVD. Finally, the proposed method was verified by real suspension bridge monitoring data. The results demonstrated that the proposed method can effectively detect a mild increase in the girder-end cumulative displacement due to FVD fluid leakage. • Proposed and validated an equivalent model for simulating the hysteresis relationship of leaked FVD. • The influence of leaked FVD locations, numbers, leakage levels and parameters on vehicle-induced GECD was revealed. • An online diagnosis method was established to realize the condition monitoring of FVD leakage in operation. • The effectiveness is verified by case study of an actual in-service suspension bridge. [ABSTRACT FROM AUTHOR]

Interfacial surface roughness can result in fluid leakage of seals, and in the design of seals it is standard to give an upper limit for the surface root-mean-square (rms) roughness amplitude h rms . However, h rms is determined mainly by the long-wavelength roughness, which is (nearly) irrelevant for the sealing. I discuss the parameters which determine the leakage of seals, and present results for static rubber seals with circular cross-section (like rubber O-rings). I also study the influence of the fluid pressure on the interfacial surface separation and the leakrate. [ABSTRACT FROM AUTHOR]

Background: Dengue fever prevalence is rising globally and it causes significant morbidity and mortality. Fluid extravasation during the critical phase of dengue haemorrhagic fever (DHF) leads to shock, multi-organ failure and death if not resuscitated appropriately with fluids. The mainstay of management is judicious fluid replacement using a guideline based, calculated fluid quota of maintenance (M) fluid plus 5% deficit (M +  5% deficit) to prevent organ hypoperfusion.Methods: We conducted an observational follow-up study in Sri Lanka from January-July 2017 to identify the fluid requirements of DHF patients and to identify whether features of fluid overload are present in patients who exceeded the fluid quota. Patients who developed DHF following admission to the place of study, were recruited and the amount of fluid received during the critical phase was documented.Results: A total of 115 DHF patients with a mean age of 30.3 (SD 12.2) years were recruited to the study. There were 65 (56.5%) males and the mean fluid requirement was 5279.7 ml (SD 735) over the 48 h. Majority of the study participants (n = 80, 69.6%) received fluid in excess of the recommended maintenance + 5% deficit and this group had higher body mass index (22.75 vs 20.76, p0.03) and a lower white cell count at the onset of the critical phase (3.22 × 103 vs 4.78 × 103, p < 0.001). The highest fluid requirement was seen within the first 12 and 24 h of the critical phase in patients requiring fluid M +  5%-7.5% deficit and ≥ M +  7.5% deficit respectively. Patients exceeding M + 5% deficit had narrow pulse pressure and hypotension compared to the rest. DHF grades III and IV were seen exclusively in patients exceeding the fluid quota indicating higher amount of fluid was given for resuscitation. Fluid overload was detected in 14 (12.1%) patients and diuretic therapy was required in 6 (5.2%) patients.Conclusions: The majority of patients received fluid in excess of the recommended quota and this group represents patients with narrow pulse pressure and hypotension. Although, fluid overload was infrequent in the study population, clinicians should be cautious when administering fluid in excess of M +  7.5% deficit. [ABSTRACT FROM AUTHOR]

The indwelling pleural catheter (IPC) is an established treatment for recurrent pleural effusion. Fluid leakage through the IPC insertion tract has been reported, but its occurrence is only limited to a short period after the procedure. Besides, the drainage efficacy of IPC may be limited by the presence of loculation in the pleural space, especially when intrapleural fibrinolytic is contraindicated. We report a case of fluid leakage through the healed entry site of IPC due to high pressure built from undrained pleural fluid locules, which was successfully treated with an additional drain targeting the largest undrained locule. [ABSTRACT FROM AUTHOR]

Background: Premature rupture of membranes occurring in previable midtrimester patients is associated with perinatal mortality, and optimal therapeutic methods are yet to be established.Objective: This study's objective was to investigate whether an elastomeric sealant, which has been used as a hemostatic agent for arterial anastomosis, could plug the uterine endocervical canal to prevent leakage of intrauterine fluid in an ex vivo model.Methods: The elastomeric sealant or fibrin glue was applied to the cervix of uteri removed for benign gynecological disease (n = 4). Normal saline was administered into the ex vivo uterine cavity through a catheter using a pressure infusion bag. Intrauterine pressure was measured using a digital pressure gauge, and the pressure at which normal saline started leaking out of the uterine cervix was compared between both the sealants.Results: No fluid leakage was observed with the elastomeric sealant until the pressure exceeded 20 kPa (150 mmHg), while the leakage onset pressure with fibrin sealant was 6.6 ± 1.8 kPa (50 ± 14 mmHg). The threshold leak pressure where the onset of liquid flow was initiated was significantly different between both the sealants (p < .0001).Conclusions: Intracervical elastomeric sealant exhibited powerful fluid leakage prevention in an ex vivo model. The sealant would have potential to prevent the leakage of amniotic fluid in pregnancies with previable premature rupture of membranes. [ABSTRACT FROM AUTHOR]

Hydrocarbon discoveries in recent years in the Upper Miocene of the Yinggehai Basin show differences in overpressure magnitude, gas and mineral components. Overpressure close to or reaching the leakage threshold has induced high system openness for one field, but the overpressure of another field remains to be safely closed. A new vision to investigate the interplay between the system openness and the gas chemical and mineralogical features were conducted. The gas components in the high openness system are rich in high maturity hydrocarbons and inorganic CO 2 , which both have heavier carbon isotopes. Low maturity gases with lighter carbon isotopes are dominant in the low openness system. The abnormal carbon isotope ratio between iso-butane and n-butane in the high openness system confirms that early low maturity leakage has generated abnormal compositional and isotopic fractionation. Although the sedimentation process was uniform in the two systems, the high openness system has rare K-feldspar grains and chlorite, but it is rich in illite/smectite mixed layers (I/S). Precipitation is characterized by ankerite and kaolinite in the high openness system, whereas the low openness system primarily consists of calcite. The strong dissolution of K-feldspar grains and chlorite should have released abundant potassium and silicon. The high abundances of I/S and kaolinite, which are both sensitive to potassium and the rarity of quartz overgrowths in the high openness system, imply that the leakage of potassium/silicon from the sandstones has induced a mass imbalance between dissolution and precipitation. Even the sandstone porosity was slightly increased by the mass imbalance in the high openness system. The risk of hydrocarbon expulsion during brine leakage cannot be ignored. [ABSTRACT FROM AUTHOR]

The potential for fluid leakage from sub-surface reservoirs has important implications for CO2 storage, hydrocarbon reservoirs and water resources. Understanding the genesis, morphology, fluid flow mechanisms and extent of fluid escape from reservoirs allows for better risking of geological resources and storage potential. Here we describe in detail the structures of fluid escape pipes from the Loyal Field, observed from a 3D full and partial stack seismic dataset. The seismic imagery suggests that the fluid escape pipes are rooted at least in the main Paleocene reservoir and by-pass the reservoir seal to cross the post Lista Formation overburden up to the intra-Neogene units. The pipes extend for a few hundred meters to a few kilometres and show varying shape and structure from blow-out structures to incipient mud volcanoes. A detailed analysis of the seismic characteristics observed both from main baseline and partial stack data allows a division of the pipes into two families: (1) seeps and pipes following structural discontinuities and (2) pipes unrelated to the pre-existing structural features. The pipes internal seismic response, the reflector termination of the main conduits and the distribution of stacked bright reflectors suggest an upward migration mechanism (during pipe birth and development), requiring a cyclic switching from non-Darcy hydrofracturing (during overpressure) to Darcy flow lateral migration (during low-pressure stage). [ABSTRACT FROM AUTHOR]

Gold-patterned glass substrates sealed to a PDMS fluidic layer is an architecture widely employed in microfluidic devices. The plasma bonding method is commonly used but presents the disadvantage of being ineffective on gold surfaces, creating a sealing weakness where solution leakage can be a problem. Frequently, alternative approaches to sealing include additional patterned layers that often require expensive cleanroom time. Here we demonstrate a sealing method involving carboxyl-terminated and amine-terminated silanes appropriate for PDMS-based device fabrication with patterned gold/glass surfaces. This cleanroom-free methodology improves solution leak pressure 37-fold compared to the standard plasma bonding technique on these patterned substrates. This bonding strategy is demonstrated in a proof-of-concept electrochemical cell enclosed in a PDMS chamber. An electrochemical method for preparing a clean and electroanalytically useful gold surface in the PDMS device is detailed. [ABSTRACT FROM AUTHOR]

Background: Liver involvement in acute dengue infection is frequently observed and sometimes leads to acute liver failure, with fatal outcomes. Many factors are thought to contribute to liver dysfunction, including hypoxic injury due to decreased perfusion, direct damage by the virus and immune mediated injury. In this study, we sought to identify the pattern in the change in liver enzymes throughout the illness and its association with the degree of viraemia, onset and extent of plasma leakage and inflammatory mediators.Methods: Serial daily blood samples were obtained from 55 adult patients with acute dengue from the time of admission to discharge and the liver function tests, viral loads and cytokines were assessed. The onset and extent of fluid leakage was measured by daily ultrasound examinations and all clinical and laboratory features were serially recorded.Results: Aspartate transaminase (AST), alanine transaminase (ALT) and gamma glutamyl transferase (GGT) levels were elevated in patients with dengue infection throughout the illness. The highest AST levels were seen on day 6 of illness and both AST and GGT levels were significantly higher in patients with severe dengue (SD), when compared to those with non-severe dengue (NSD) on day 5 and 6 of illness. Three patients with SD had AST and ALT values of >1000/IU in the absence of any fluid leakage or a rise in the haematocrit (≥20 %). The peak of the AST levels and the lowest serum albumin levels were seen 24 h before the maximum fluid leakage and 24 h after the peak in viraemia. Both serum IL-10 and IL-17 levels were elevated during early illness and were significantly higher in those with SD when compared to NSD.Conclusion: Dengue associated liver injury appears to peak around day 6 and 7. Therefore, liver function tests done at earlier dates might not reflect the extent of liver involvement in acute infection. Since severe liver involvement can occur in the absence of fluid leakage, after the peak viraemia, and since it is associated with high IL-17 and IL-10 levels, possible immune mechanisms leading to hepatic damage should be investigated. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare fluid leakage across endotracheal tube cuffs using a three-dimensional (3D)-printed human tracheal model that anatomically simulates the human trachea. We made two models based on computed tomography data of the neck and chest. Using a Mallinckrodt Hi-Lo™ (HL), ThinCuff (TC), and Mallinckrodt TaperGuard™ (TG), we sequentially measured the amount of fluid leakage across each endotracheal tube cuff after applying saline or viscous liquid above the cuff. The TG allowed significantly less leakage than the HL and TC with both saline and the viscous liquid. Our study, using a 3D-printed tracheal model, indicated that a conical-shaped endotracheal tube cuff significantly reduces fluid leakage across the cuff compared with conventional cylindrical-shaped cuffs made of polyurethane or polyvinylchloride, contrary to the results of a previous study using a solid cylindrical structure. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effects of valved and non-valved cannulas on intraocular pressure (IOP), fluid leakage, and vitreous incarceration during simulated vitrectomy. Methods: Three-port pars plana incisions were generated in six rubber eyes using 23-, 25-, and 27-gauge valved and non-valved trocar cannulas. The models were filled with air and IOP was measured. Similar procedures were followed for 36 acrylic eyes filled with saline solution. Vitreous incarceration was analyzed in eleven rabbit and twelve porcine cadaver eyes. Results: In the air-filled model, IOP loss was 89%-94% when two non-valved cannulas were unoccupied versus 1%-5% when two valved cannulas were unoccupied. In the fluid-filled model, with non-valved cannulas, IOP dropped while fluid leaked from the open ports. With two open ports, the IOP dropped to 20%-30% of set infusion pressure, regardless of infusion pressure and IOP compensation. The IOP was maintained in valved cannulas when one or two ports were left open, regardless of IOP compensation settings. There was no or minimal fluid leakage through open ports at any infusion pressure. Direct microscopic analysis of rabbit eyes showed that vitreous incarceration was significantly greater with 23-gauge non-valved than valved cannulas (P,0.005), and endoscopy of porcine eyes showed that vitreous incarceration was significantly greater with 23-gauge (P,0.05) and 27-gauge (P,0.05) non-valved cannulas. External observation of rabbit eyes showed vitreous prolapse through non-valved, but not valved, cannulas. Conclusion: Valved cannulas surpassed non-valved cannulas in maintaining IOP, preventing fluid leakage, and reducing vitreous incarceration during simulated vitrectomy. [ABSTRACT FROM AUTHOR]

Abstract: We use a high resolution 3D seismic dataset covering 970km2, over the Snøhvit and Albatross gas fields of the Hammerfest Basin in the Barents Sea, in order to investigate the basin fault architecture and identify potential fluid pathways of deeper thermogenic gas and fluids. A polygonal fault (PF) interval not previously published is described in the three non-connected blocks within Campanian sequences, which could imply a permeable complex network of pathways that facilitate the vertical migration of hydrocarbons along the fault planes. The dominant orientation of the PFs is similar to the main regional tectonic fault trend (EW), suggesting a tectonic influence upon the development of polygonal faults, although some individual PFs locally seem to develop orthogonally to regional 1st order tectonic faults. A lithologic control on the occurrence of PF patterns is evident as none are observed within calcareous low clay sediments. The PF networks present three main orientations: dominant ENE/WSW, secondary NNE/SSW and a minor NE/SW. Paleocene–Early Eocene Faults (PEEFs) prevail above the PF networks, with coinciding ENE/WSW fault strikes, interpreted as preferential reactivation of the PF systems. Numerous amplitude anomalies, linked to the escape of thermogenic fluids from the Jurassic reservoir were identified. We present a conceptual model where the 1st order reactivated faults and PEEFs acted as pathways for fluids from the deeper hydrocarbon reservoirs. The PEEFs are partially sealing with a lateral migration component. Interplay between the PFs, PEEFs and the 1st order reactivated faults focuses the fluids vertically along the polygonal fault traces creating a wider diffuse zone which form large gas cloud anomalies in the seismic data. [Copyright &y& Elsevier]

Abstract: The paper develops an analytical result for the flow through a single fracture under a hydraulic gradient between the two aquifer regions and takes into account permeability characteristics of all components of the system. Non-dimensional results are presented to illustrate the influence of the permeability mis-match between the two geologic formations and the permeability and geometry of the fracture on the flow rate through the fracture. The analytical result is then used to develop additional results for leakage through a swarm of vertically aligned hydraulically non-interacting fractures and a damaged region containing a densely spaced array of vertically aligned fractures and worm hole type features in the caprock. The work presents a convenient result for the estimation of leakage from storage formations in geoenvironmental applications. [Copyright &y& Elsevier]

Thyroid fine needle biopsy (FNB) is the procedure of choice for the management of thyroid nodules. Serious complications after FNB are rare, but there is also an underestimation of complication risk because of record, selection and publication biases. Hypothesis: Apart from the well-documented post-FNB complications, we hypothesized that there are potential complications following FNB, albeit supported by limited evidence in the literature. According to our hypothesis, there may be five distinct expected rare complications: 1) cyst fluid leakage; 2) anaphylactic reaction; 3) pneumothorax; 4) thromboembolism and 5) needle tract seeding of medullary thyroid carcinoma (MTC) or thyroid lymphoma. Conclusions: Cyst fluid leakage and pneumothorax may be of minimal clinical significance. Needle tract seeding of MTC or thyroid lymphoma may not have significant clinical consequences, if someone considers the easiness and effectiveness of surgical removal of needle tract seeding in cases of differentiated thyroid carcinoma. On the contrary, anaphylactic reaction or thromboembolism may be life-threatening. The performers of thyroid FNB are hereby encouraged to publish these complications, if they ever occur, because awareness of them could render FNB even safer. Hippokratia 2011; 15 (2): 116-119 [ABSTRACT FROM AUTHOR]

Purpose: Standard polyvinylchloride (PVC) endotracheal tube (ETT) cuffs do not protect from aspiration across the cuff, a leading cause of ventilator-associated pneumonia (VAP). In a long-lasting in vitro study we compared the effect of different cuff materials (PVC, polyurethane, and guayule latex), shapes (cylindrical, conical), and positive end expiratory pressures (PEEP) in reducing fluid leakage across the cuff. Methods: We compared fluid leakage across a cylindrical double-layer guayule latex prototype cuff, three cylindrical PVC cuffs (Mallinckrodt Hi-Lo, Mallinckrodt HighContour, Portex Ivory), one conical PVC cuff (Mallinckrodt TaperGuard), and two polyurethane cuffs (Mallinckrodt SealGuard, conical; Microcuff, cylindrical). Ten centimeters of dyed water was poured above the cuffs inflated (pressure 30 cmHO) in a vertical cylinder (diameter 20 mm). A respiratory circuit connected the bottom of the cylinder to a breathing bag inflated at four pressures (PEEP = 0, 5, 10, 15 cmHO). Pictures were taken every 60 s for 24 h to measure leakage as a reduction in the water column above the cuff. Five new ETTs of each type were tested. Results: The guayule latex cuffs showed no leakage at all the PEEP levels. Both the cylindrical and conical polyurethane cuffs showed limited leakage (2.1 ± 1.8 cm of water) only for PEEP zero. The PVC cuffs showed reduced leakage with increasing PEEP: 8.4 ± 1.5, 7.8 ± 2.2, 2.2 ± 1.0, and 0 cm of water at 0, 5, 10, and 15 cmHO, respectively. Among all the PVC cuffs, the conical shape ensured higher sealing properties. Conclusions: The guayule latex cuffs always prevented fluid leakage; the polyurethane and PVC cuffs required incremental levels of PEEP to prevent fluid leakage ever-present at zero PEEP. [ABSTRACT FROM AUTHOR]

The paper discusses modeling of a multi-layer coal seam under hydrodynamic action based on the coupled equations of poroelasticity and filtration with the nonlinear relationship of permeability and porous pressure. The calculations by the finite element method use correspondence between the poroelasticity and thermoelasticity equations. The influence of input data on the size of a degassing hole area is analyzed for the couple problem and pure filtration problem. [ABSTRACT FROM AUTHOR]

Abstract: We use the formalism developed by Persson et al. [Contact area between a viscoelastic solid and a hard, randomly rough, substrate. J Chem Phys 2004;120(18):8779–93], which we briefly review for the reader convenience, to calculate the fluid leakages in seals. The methodology makes use of the percolation theory and theory of contact mechanics to show how the statistical properties of the surface, the applied load and the geometry of the seal affect the leakages in such systems. The problem is relevant in a countless number of applications, e.g. in ball valves, or common rail systems. The basic idea is to describe the nominal contact area as a square lattice where each square can be black or white depending on whether contact between the two surfaces takes place or not. The probability to find a black site is then equal to the ratio between the apparent contact area at a given magnification and the nominal contact area. Since the apparent contact area decreases as the magnification is increased, a critical value of the magnification exists at which the probability to find a white square reaches the critical value given by the percolation theory. When this happens, a percolation channel is formed and fluid leakage occurs. [Copyright &y& Elsevier]

Aim To investigate the sealing quality of ProRoot Endo Sealer, a calcium silicate-based sealer and its morphologic characteristics after immersion in a phosphate-containing fluid (PCF). Methodology Single-rooted canals were filled with gutta-percha and either ProRoot Endo Sealer or two commercially available zinc oxide eugenol (ZOE)-based and epoxy resin-based sealers. The sealers were allowed to set for 6 days and the filled teeth were immersed in PCF for 24 h before fluid leakage evaluation. After initial leakage evaluation at the 7th day, each filled root was restored and reimmersed in PCF for 28 days before the second phase of leakage evaluation at 35 days. Cryofractured specimens of additional teeth filled with the three sealers were examined using scanning electron microscopy after immersion in PCF for the two periods. Results One-way repeated measuresanova and Tukey test revealed significant differences between the ZOE-based sealer at 35 days and the calcium silicate-based sealer at 35 days ( P < 0.001), and between the ZOE-based sealer at 7 days and the calcium silicate-based sealer at 35 days ( P = 0.001). No difference was found between the epoxy resin-based sealer and the calcium silicate-based sealer after both storage periods. Cryofractured calcium silicate-based sealer specimens demonstrated apatite-like crystalline deposits along the apical and middle thirds of the canal walls via transformation from amorphous calcium phosphate-like precursors. Conclusions ProRoot Endo Sealer is comparable in sealing quality to the epoxy resin-based sealer and seals better than the ZOE-based sealer after immersion in PCF. The calcium silicate-based sealer also demonstrates ex vivo bioactivity when it comes into contact with phosphate ions. [ABSTRACT FROM AUTHOR]

Background: Cardiopulmonary bypass (CPB) is associated with increased fluid filtration occasionally leading to post-operative organ dysfunction. One of the factors determining fluid filtration is the capillary hydrostatic pressure which depends on arterial pressure, venous pressure and pre- to post-capillary resistance ratio. The purpose of this study was to assess whether lowering of the mean arterial pressure and/or the central venous pressure could reduce fluid extravasation during normothermic and hypothermic CPB. Methods: Seven piglets were given nitroprusside to a mean arterial pressure of 35–40 mmHg during 60 min of normothermic and 90 min of hypothermic CPB (LP group). They were compared with a control group (C group, n = 7) without blood pressure interventions. Blood chemistry, net fluid balance, plasma volume, colloid osmotic pressure in plasma and interstitial fluid, intravascular protein masses, fluid extravasation rate and total tissue water content were measured or calculated. Results: Mean arterial pressure was significantly lower in the LP group than in the C group during CPB. Plasma volume tended to increase in the LP group ( P > 0.05), but remained essentially unchanged in the C group. Net fluid balance in the LP group was more positive than in the C group 30 min after CPB start [1.02 (0.15) vs. 0.56 (0.13) ml/kg/min (Mean (SEM) P < 0.05)]. Fluid extravasation rate tended to be higher in the LP group and total tissue water content of the gastrointestinal tract, left myocardium and skin was significantly elevated compared with the C group. Conclusion: During CPB, lowering of the mean arterial pressure using nitroprusside did not reduce fluid extravasation. On the contrary, the data may implicate an increase in edema formation during low pressure CPB. [ABSTRACT FROM AUTHOR]

Background: Hypothermia, commonly used for organ protection during cardiopulmonary bypass (CPB), has been associated with changes in plasma volume, hemoconcentration and microvascular fluid shifts. Fluid pathophysiology secondary to hypothermia and the mechanisms behind these changes are still largely unknown. In a recent study we found increased fluid needs during hypothermic compared to normothermic CPB. The aim of the present study was to characterize the distribution of the fluid given to maintain normovolemia. In addition, we wanted to investigate the quantity and quality of the fluid extravasated during hypothermic compared to normothermic CPB. Methods: Two groups of anesthetized piglets were studied during 2 h of hypothermic (28 °C) (n=7) or normothermic (38 °C) (n=7) CPB. Net fluid balance (input-output) was recorded. Changes in colloid osmotic pressures of plasma (COPp) and interstitial fluid (COPi), plasma volume (PV), hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV), s-osmolality, s-albumin and s-total protein was followed throughout the experiments. Fluid extravasation rate was calculated. In addition, total tissue water content was measured and compared with a control group (n=6) (no CPB). Results: During hypothermic compared with normothermic CPB, the average net positive fluid balance from 10–120 min of extracorporeal circulation was 1.35±0.06 ml · kg-1 · min-1 and 0.33±0.03 ml · kg-1 · min-1 respectively (P<0.0001). We found a marked increase in fluid extravasation during hypothermic CPB. The extravasation rate during hypothermia was 1.8±0.2 ml · kg-1 · min-1, (1st hour) and 1.1±0.2 ml · kg-1 · min-1 (2nd hour) compared with 0.8±0.2 ml · kg-1 · min-1, and 0.1±(0.1) ml · kg-1 · min-1 during normothermia, respectively (P<0.01). The total intravascular protein and albumin masses remained constant in both groups. Following hypothermic CPB, the water content increased significantly in all tissues and organs. Conclusion: During hypothermic CPB an increased extravasation of fluid from the intravascular to the interstitial space was found. As no leakage of proteins could be demonstrated, based on stable values for albumin and protein masses throughout the experiments, the extravasated fluid contained mainly water and small solutes. [ABSTRACT FROM AUTHOR]

This study used an airway model to compare the ability of a pediatric endotracheal tube with a taper-shaped cuff to prevent microaspiration relative to endotracheal tubes with conventional cuffs. Four different types of 5.0-mm inner diameter cuffed pediatric endotracheal tubes (taper-shaped cuff [ Taper], high-volume low-pressure [ Hi- Lo], middle-volume low-pressure [Intermediate], and low-volume low-profile [ Lo- Pro]) were fixed within vertically placed acrylic tubes. The cuffs were maintained at 10, 20, or 30 cmH2O pressure and 3 mL of simulated stomach contents was added to the top of the cuffs. The volume of leakage around the cuffs after 5 min and 4 h was measured. After 5 min, the volume of leakage was significantly lower with the Taper than with the Hi- Lo, Intermediate, or Lo- Pro at all pressure settings. After 4 h, leakage was significantly lower with the Taper than with the other three tubes regardless of initial cuff pressure ( P < 0.05). [ABSTRACT FROM AUTHOR]